Any action (in some cases including using items) consumes a certain amount of AP. A unit cannot execute an action if there's not enough AP. If the unit has zero AP, that unit's turn is over. The player however, may end the unit's turn early. When it is that player's turn again, AP is replenished. AP may be partially restored or fully restored, and in some games, restoration may bring the unit's AP over the maximum limit that unit normally has.

Units, both the player's and the enemy's, are placed upon a map of an area. Both sides take turns moving every character they have at their disposal.

When an AP system is in effect, both sides use AP.

Say it is the player's turn. The player wants to move a unit with 15/15 AP three spaces with each space consuming 1 AP. There is 12/15 AP left.

The player wants to attack a nearby enemy:

If the attack consumes 10 AP, there will 2/15 AP left. Since the unit doesn't have enough AP to launch another attack, the player can decide to move the character away or end the turn (normally most games have the character's turn ending immediately after attacking).

If the attack consumes 12 AP, there will be 0/15 AP left. The unit's turn ends immediately.

When the player's turn comes around again, it will have 15/15 AP.

To add a sense of realism, the more stressful the action is, the more AP is consumed. For example, in land based combat, having a character move over rugged terrain may consume more AP than moving over smooth terrain. Using more powerful attacks also consumes more AP. In the Front Mission series, using a shotgun consumes a different amount AP than using a sub-machine gun or a rifle.

Another idea of AP is to use it as a sort of stamina meter in real time combat games. In Star Ocean: Till the End of Time, a battle mechanic employs a stamina bar known as Fury. Attacking consumes Fury, and if the character does not have enough, he or she cannot attack. Standing still recovers Fury. In other games such as first-person shooters, a stamina meter may be used for actions such as jumping or sprinting. Normal actions won't affect the meter, apart from (sometimes) hampering its recovery rate (such as running after a sprint).